1. Field of the Invention
The invention relates to catheters which are adapted to be inserted in ducts and passages within the body as well as blood vessels including arteries and veins for the removal of blockages, obstructions, occlusions, etc. or the like therein. More in particular, the invention relates to laser angioplasty, the use of a laser to vaporize plaque in coronary, femoral and other arteries. Laser angioplasty comprises the directing of a catheter which is adapted to transmit a laser beam, i.e., laser energy, into a blood vessel and advancing the free end of the catheter within the blood vessel to the location of an occlusion or arteriosclerotic plaque within the blood vessel. The catheter delivers laser energy to the location to vaporize the occlusion, thereby opening obstructed blood vessels.
The use of the intense and concentrated energy of a laser within a portion of the body such as a blood vessel presents the possibility of damage to the surrounding tissue. In the case of a blood vessel, possible perforation of the blood vessel is of chief concern.
2. Description of the Prior Art
Conventional catheters for laser angioplasty have a flexible outer tube which can be inserted into a blood vessel. Within the outer tube is disposed a bundle of optical fibers which extend to adjacent the distal end of the outer tube. A laser is connected to the bundle for transmitting laser energy to an occlusion within the blood vessel. Debris resulting from the vaporizing of the occlusion by the laser can be removed by applying suction to the outer tube.
U.S. Pat. No. 4,207,874, issued June 17, 1980, for a "Laser Tunneling Device" is an example of a catheter having a bundle of optical fibers. The catheter is adapted to be advanced within a blood vessel to adjacent an ooclusion or calcified plaque for the application thereto of the energy of a laser. Suction can be applied to the laser to remove the debris resulting from the vaporization of the occlusion.
U.S. Pat. No. 4,224,929, issued Sept. 30, 1980, for "Endoscope with Expansible Cuff Member and Operation Suction", discloses an endoscope adapted to be placed in a blood vessel. A pair of cuff members spaced apart from one another and disposed adjacent the distal end of the endoscope is adapted to be expanded to contact the inner walls of the blood vessel and form a chamber between the cuff members. A procedure such as observation, surgical treatment, etc. can then be performed within the chamber formed by the cuff members with the blood vessel.
U.S. Pat. No. 4,240,431, issued Dec. 23, 1980, for "Laser Knife" discloses a device using laser energy for the incision or excision of an affected part of the body. In order to prevent the laser energy from causing undesirable cautery or piercing of normal tissue adjacent that which is to be treated, the laser energy is intercepted by a receiving surface, once the cutting procedure is completed.